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Hi Friends,

I am from the tropics; Kerala, India.  New to Aquaponics- ; since 2nd October 2015 to be precise.

Can I get your view points in the following issue, pl.

1.  Is it necessary that we have to protect FT from direct sunlight falling on the water surface ? 

2.  What is the best pH range advised for Tilapia ?  Will it be all right if the pH level drops below  7 ?

Very many thanks in advance.

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I recently added extra fish to my FT and an extra growbed - and experienced an algae bloom.

Following advice here and on internet i've painted the FT, GB - the algae dissapear overnight.  I've not painted the DT - but there is a crst of algae crusted to the wall - but water is clear.

Some comments elsewhere on this site suggest that the algae will dissapear once the system reach equilibrium.

Regards,

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6.2 to 7.0 is generally recommended for plants and Tilapia seem to thrive in that range.  I believe a higher PH, 8.0 or so, is preferred for breeding but generally that is done separately from the aquaponics system.  In normal circumstances, it is not necessarily to lower PH because nitrification continuously lowers PH.  If you accidentally raise your PH too high, your system should bring it back down.  

What I use to raise PH is Calcium Hydroxide and Potassium Bicarbonate at 50/50.

For more, see below, copied from Start Here, Rules of Thumb (upper left on this site, home).

pH

  • Target a pH of about neutral, or 6.8 – 7.0, in your aquaponic system. This is a compromise between the optimal ranges of the fish, the plants, and the bacteria. For fish, this is a pH of around 6.5 to 8.0. For plants, this is a pH of around 5.0 to 7.0 and for bacteria it is a pH of 6.0 to 8.0.
  • Test pH at least weekly, and as frequently as 3 – 4 times per week, using your API Freshwater Master Test Kit.
  • During cycling pH will tend to rise.
  • After cycling your systems, pH will probably drop below 7.0 on a regular basis and require being buffered up. If you need to lower pH it is generally because of the water source (such as hard ground water) or because you have a base buffer in your system (egg shells, oyster shell, shell grit, incorrect media).
  • Best methods for raising (buffering) pH if it drops below 6.4
    • Calcium hydroxide, hydrated lime or “builder’s lime”.
    • Potassium carbonate (or bicarbonate) or potassium hydroxide (pearlash or potash)
    • If possible, alternate between these two each time your system needs the pH raised. These also add calcium and potassium, which your plants will appreciate.
    • You can purchase these compounds in small quantities as our AquaUp pH Raising Kits
    • While they work, be cautious about using natural Calcium Carbonate products (egg shells, snail shells, sea shells). They don’t do any harm, but they take a long time to dissolve and affect the pH. So, you add it, check pH two hours later and nothing has changed, so you add more. Then suddenly, the pH spikes because you have added so much.
  • Best methods for lowering pH, in order of preference, if it goes above 7.6
    • Acids such as nitric or phosphoric as the plants can use the nitrate or phosphate produced.
    • Our AquaDown pH Lowering Solution is made of phosphoric acid.
    • Other acids, such as vinegar (weak), hydrochloric (strong), and sulphuric (strong) as a last resort as directly adding these acids to your system could be stressful for your fish.
  • Avoid adding anything to your system containing sodium as it will build-up over time and is harmful to plants.
  • Do not use citric acid as this is anti-bacterial and will kill the bacteria in your bio-filter.



Pieter Swanevelder said:

I recently added extra fish to my FT and an extra growbed - and experienced an algae bloom.

Following advice here and on internet i've painted the FT, GB - the algae dissapear overnight.  I've not painted the DT - but there is a crst of algae crusted to the wall - but water is clear.

Some comments elsewhere on this site suggest that the algae will dissapear once the system reach equilibrium.

Regards,

Thank you for your response, Mr. Pieter S.  I think I should paint my FT as well.  I received an advise that  FT should be insulated from sunlight where as GB needs it badly.  Pending painting, i have provided a skirting to FT.  

B'regs



George said:

6.2 to 7.0 is generally recommended for plants and Tilapia seem to thrive in that range.  I believe a higher PH, 8.0 or so, is preferred for breeding but generally that is done separately from the aquaponics system.  In normal circumstances, it is not necessarily to lower PH because nitrification continuously lowers PH.  If you accidentally raise your PH too high, your system should bring it back down.  

What I use to raise PH is Calcium Hydroxide and Potassium Bicarbonate at 50/50.

For more, see below, copied from Start Here, Rules of Thumb (upper left on this site, home).

Thank you , Mr. George, this data was the one I have been looking for,  all along.  Now I have to make a closer follow up of the pH in the system.  A few egg-shells in GB shall be advantageous to control residual acidity brought in by the NO2 / NO3 ions, right ?  I have some lime stock also, if needs be. 

B'regs

pH

  • Target a pH of about neutral, or 6.8 – 7.0, in your aquaponic system. This is a compromise between the optimal ranges of the fish, the plants, and the bacteria. For fish, this is a pH of around 6.5 to 8.0. For plants, this is a pH of around 5.0 to 7.0 and for bacteria it is a pH of 6.0 to 8.0.
  • Test pH at least weekly, and as frequently as 3 – 4 times per week, using your API Freshwater Master Test Kit.
  • During cycling pH will tend to rise.
  • After cycling your systems, pH will probably drop below 7.0 on a regular basis and require being buffered up. If you need to lower pH it is generally because of the water source (such as hard ground water) or because you have a base buffer in your system (egg shells, oyster shell, shell grit, incorrect media).
  • Best methods for raising (buffering) pH if it drops below 6.4
    • Calcium hydroxide, hydrated lime or “builder’s lime”.
    • Potassium carbonate (or bicarbonate) or potassium hydroxide (pearlash or potash)
    • If possible, alternate between these two each time your system needs the pH raised. These also add calcium and potassium, which your plants will appreciate.
    • You can purchase these compounds in small quantities as our AquaUp pH Raising Kits
    • While they work, be cautious about using natural Calcium Carbonate products (egg shells, snail shells, sea shells). They don’t do any harm, but they take a long time to dissolve and affect the pH. So, you add it, check pH two hours later and nothing has changed, so you add more. Then suddenly, the pH spikes because you have added so much.
  • Best methods for lowering pH, in order of preference, if it goes above 7.6
    • Acids such as nitric or phosphoric as the plants can use the nitrate or phosphate produced.
    • Our AquaDown pH Lowering Solution is made of phosphoric acid.
    • Other acids, such as vinegar (weak), hydrochloric (strong), and sulphuric (strong) as a last resort as directly adding these acids to your system could be stressful for your fish.
  • Avoid adding anything to your system containing sodium as it will build-up over time and is harmful to plants.
  • Do not use citric acid as this is anti-bacterial and will kill the bacteria in your bio-filter.

Egg shells can be dried and ground to small particle size, which will cause them to have more of an immediate effect on PH.  

If you can acquire calcium hydroxide and potassium bicarbonate, that is what I recommend.

I add them to the grow bed, at the inlet.  These days, I use them primarily in compost, for ground gardening.

See Jim Fisk's posts in the IBC group - he uses wood ashes to raise PH.

Robert Morris said:

Egg shell particles go in the tank or the bed or does it mater?

Thank you, Mr. Robert M.

I have bought a packet of Cal. Hydroxide as you suggested,  for emergency.  

By the way, a few shells in the GB shall go into solution very very slowly if the pH is about 6.2 plus only.This will provide us a buffer effect in the system.  Don't you think so ?   As the shell is not hard, this shall not cause any trouble with the pump either. 

B'regs

Good to see you here, UVS Menon.  I am just a few kilometers away from your place.  

Hope you already received the answers for your questions.  In my experience, I noticed pH tanks rapidly when there are less plants in the system.  Lime amendments can help too.

Some green algae on some of the side-walls, IMO, is beneficial.  Tilapia will graze on them - so that's no problem.
I have been doing Aquaponics full time since 2012.  You are welcome to look at my activities and updates here at http://facebook.com/aquaponicsfuturist

Yes, definitely and 6.2 is a good PH level for your plants.

U V S MENON said:

By the way, a few shells in the GB shall go into solution very very slowly if the pH is about 6.2 plus only.This will provide us a buffer effect in the system.  Don't you think so ?   

I could repeat all I've seen on YouTube or read in this Forum but my recommendation would be go to https://www.youtube.com/watch?v=zP1rUMyklyc. This guy has dozens of detailed videos on every aspect of aquaponics.



Jeff S said:

I could repeat all I've seen on YouTube or read in this Forum but my recommendation would be go to https://www.youtube.com/watch?v=zP1rUMyklyc. This guy has dozens of detailed videos on every aspect of aquaponics.

Thank you Jeff S for your reply.  I went thru the You Tube on your advice; sure he was a lot of solutions ready for our probs.

B'regs

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